Question about 1999 GMC Sierra

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Heater poor heat,is it hard to change heater box? my fan is broken out,

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Yes the entire dash must be removed to access the climate control ducting

Posted on Feb 14, 2012

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Heater doesn t blow out any heat or air

If it is not blowing at all your problem is with the fan. It is mounted up under the passenger side. Typically about 6 screws hold on the cover and the fan is right under it. Pretty easy fix. When the fan is out I would test it first....after thought here...did you check the fuses?

Mar 02, 2014 | 1999 Pontiac Sunfire

1 Answer

Turn on power to heater & nothing but the power light comes on, please help

There's a heater core box where radiator coolant passes through. When you turn on the heater, the fan on the heater core box blows air through the core, then the air is heated up and it passes through the air ducts, which leads to the windshield defroster, the vents, or your feet depending on where you set the control. If you're not feeling heat, either the fan on the heater core box is not working, or there's restriction on the coolant hoses and hot coolant isn't passing through the heater core box. Remove and diagnose the heater core box to ascertain the coolant lines are not blocked and the fan is fully operational. If the heater core box is OK, then the hoses have restriction to prevent hot coolant from passing through the heater core box.

Nov 26, 2013 | Plymouth Voyager Cars & Trucks

2 Answers

Is there a fuse or relay for the heater in my 2002 ford expedition

No hot air is due to low coolant, or even poor coolant flow. The engine heats up the coolant, and it passed through your heater core, and the heater blower motor pushes air through the heater core to warm up the air. If your "fan"is working, but the air is cold, make sure your coolant level is good.

Dec 08, 2011 | 2002 Ford Expedition

1 Answer

We have a 2005 Grang prix and the heater will not but out much heat. We checked the coolent and it is full

Open the hood and with the heater running(be careful PLEASE), feel the lines going to the heater core(2 hoses running to the firewall, to the blower motor). Is one of them hot? If both are cool, your relay valve to allow coolant to the heater core is stuck. It will have to be replaced. Is the blower fan running( that's the fan in front of the firewall)? If the valve opens but no fan running, you will not get hardly any heat. If all that is working, You have a problem with the vent control valve(that will open the hose duct to allow heat to go through the vents). It works off of vacuum. A hose may have broken (they are made of rubber), or it may be just stuck. Check these first, before looking at the heater core. I hope this helps you

Dec 30, 2010 | 2005 Pontiac Grand Prix

2 Answers

Ford Puma Heating Problem

look under the dash for a big black box the fan will be in that box but first check the wires for good connections and power

Feb 15, 2010 | 2001 Ford Focus

2 Answers

No heat from the heater

Let me add a new twist. My 2003 has a bad heater/A.C. control module. Try moving the fan speed from off to 5 as fast as you can, like 5 times then see if you have heat or not. I bet you do.

Dec 30, 2009 | 2003 Chevrolet Impala

1 Answer

Had radiator flush. Even before this was done,

A few things to consider when diagnosing poor heater
  • Flushing the radiator doesn't do much in terms of heat. The heater core should be flushed to get rid of anything accumulated in there over the years.
  • How hot is the engine actually getting? If the thermostat is stuck open the engine may never reach proper operating temperature.
  • With the engine at operating temperature feel the hoses going into the heater core, are they hot? Some vehicles use a heater control valve that only flows coolant through the heater core when activated. They work off of vacuum and it isn't uncommon to find a broken vacuum line at the valve.
  • Are the doors in the heater box operating correctly? Can you hear the heater door inside the dash open when you select heat?
I hope this helps in getting your heat to work for the upcoming season.

Oct 06, 2009 | 1999 Oldsmobile Intrigue

1 Answer

2001 XG300 heater fan blows, but only cold air....

most cars have a control box which is nothing more than a plastic box with flaps in it to direct the air to the appropriate duct. a lot of vehicles use vacuum to power the movement of th flap. ck for broken or leaking vacuum lines.also ck for a broken actuater arm on the box. these are ussualy made of plastic.

Sep 07, 2009 | 2001 Hyundai XG300

3 Answers

Heater fan regulation

2002 Grand Caravan. The rear heater also has a resistor for the fan speed control.(3 speed) It is located under the rear passenger side plastic cover. You can take off the rear tail gate lower plastic piece and this will let you pull out the side panel. You can reach in and take out the two screws that hold in the resistor and unhook the wiring adapter. You do not have to take off the whole side panel as you can reach in from the back. The resistor unit can be bought at you local dodge dealer.

Nov 30, 2008 | 2002 Dodge Grand Caravan

1 Answer

Heat works poorly on fan 1 and 2 and no heat 3,4,5 fan speed

my truck did the same thing. i unhooked the two heater core hoses, and then back flushed the heater core with a garden hose. seems to work pretty good so far

Nov 02, 2008 | 2000 Chevrolet Silverado 1500

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